Asbestos is a hydrous silicate mineral which is fibrous in nature and is abundant in magnesium. It is has been widely used as a building material such as a millboard, an asbestos slate, or the like, a fireproof material, a refractory material, a thermal insulation material, an electrical insulating material, an electrolytic membrane material, a brake lining material, or the like.
In particular, asbestos is widely used as being excellent in heat resistance, insulation property, abrasion resistance, tensile strength, and resistance to acid or alkali chemical substances, and being very inexpensive. However, as it has been recently found that asbestos is carcinogenic, it is gradually thrown out. Furthermore, a research is in progress to replace asbestos.
Representative examples of the research result include Korean Utility Model Registration No. 20-0351515 disclosing a nonflammable sheet in which carbon fiber sheets are bonded to both surfaces of a silica fiber sheet by an adhesive, Korean Utility Model Registration No. 20-0435418 disclosing a construction grass (fiber) cement board in which a fiber obtained by pulping grasses or herbaceous plants is mixed with cement and water to thereby produce a thermal and sound insulation material which is used for interior and exterior construction and is resistant water and fire, and Korean Patent Laid-Open Publication No. 2007-0065854 disclosing a method for producing a sound-absorbing material using a recycling synthetic fiber waste and a sound-absorbing board for use in building.
The above-mentioned prior arts partially solve the harmfulness problem occurring in asbestos and have an additional function of a building material. However, such conventional prior arts still entail a drawback in that since they include raw materials from which a harmful substance can be released partially, the harmfulness problem is not solved completely.
Accordingly, the present inventors have made extensive efforts to solve the problems associated with the conventional prior arts and, as a result, have found that a nonflammable building material which are not harmful to the human body can be prepared by subjecting silica, limestone, and albite, or wollastonite and albite, which are natural minerals to a series of processes including grinding, melting, spraying, and molding, thereby completing the present invention.